Fossils from the Miura Peninsula and its Immediate North. M) 



Fossil occurrence. — Koshiba Zone (Koshiba). 



34 Mitra (Costellaria) emmae, Yokoyama. 

 Pl. VI. Fig. 4. 



A single example, 12 millim. in height and 4,5 millim. in 

 diameter. 



The shell is small, rather solid and fusiform in shape, with 

 the body-whor] nearly twice as long as the spire. The whorls are 

 eight in number and, with the exception of the first two smooth 

 rounded ones, flattened in the upper half and convex in the 

 lower. They are longitudinally plicate; the plica' which number 

 about twenty-two on the penultimate whorl, are low, roof-like and 

 somewhat oblique, being separated by broad v-shaped valleys 

 which show fine, indistinct, spiral lines. The base is to a greater 

 part smooth, the only ornaments being the weak continuations of 

 the longitudinal plicie and a few spiral ribs found at its extreme 

 end which are runners of the oblique folds of the inner lip. The 

 latter number four in all, decreasing in size from above downward. 

 Outer lip broken. 



This species is much like a shell figured by Smith as a variety 

 of Mitra inermis Reeve in the Proc. Zool. Soc. London, 1879 (pl. 

 XX, figs. 53, 53 a). But in the latter the lower half of the whorls 

 is not convex as in ours. 



Fossil occurrence. — Miyata Zone (Shimo-Miyata). 



Family Fasciolariidae. 



Genus Fa sus, Lamarck. 



35. Fusus niponicus, Smith. 



Pl. II. Fig. 7. 



l<\isus niponicus. Sowerbt, Thes. Conch., vol. IV, p. 79, pl. 411, fig. 70. Smith, Proc. Zool. 

 Soc. London, 1879, p. 203, pl. XX, fig. 12. 



Two young specimens, one of which is imperfect but larger, 

 measuring 28 millim. in height, while the other more perfect one 

 measures 23 millin. in height. The whorls are about eight in 

 number, of which the uppermost two are embryonal, smooth and 



